Thin disk of co-rotating dwarfs: a fingerprint of dissipative (mirror) dark matter?

TL;DR

This paper explores how dissipative mirror dark matter could explain the observed thin, co-rotating disk of dwarf galaxies around M31, which is challenging to reconcile with collisionless dark matter models.

Contribution

It proposes that dissipative dark matter, like mirror dark matter, provides a natural explanation for the dark matter content in tidal dwarf galaxies.

Findings

Mirror dark matter can account for dark matter in tidal dwarf galaxies.

Dissipative dark matter models explain the thin, co-rotating disk structure.

Supports the viability of mirror dark matter as a dark matter candidate.

Abstract

Recent observations indicate that about half of the dwarf satellite galaxies around M31 orbit in a thin plane approximately aligned with the Milky Way. It has been argued that this observation along with several other features can be explained if these dwarf satellite galaxies originated as tidal dwarf galaxies formed during an ancient merger event. However if dark matter is collisionless then tidal dwarf galaxies should be free of dark matter - a condition that is difficult to reconcile with observations indicating that dwarf satellite galaxies are dark matter dominated. We argue that dissipative dark matter candidates, such as mirror dark matter, offer a simple solution to this puzzle.